> Can someone tell me how I can find out who owns any certain domain name [...]?
> Is there a way to look up if the url is actually owned by the people trying to sell it?

https://www.whois.com/whois/

> I [...] would like to keep an eye on the domain name I am interested in obtaining,
> to know when it is about to expire, and maybe get lucky enough to purchase it on
> the exact date and time when it expires.

https://en.wikipedia.org/wiki/Domain_drop_catching#Redemption_Grace_Period_.28RGP.29